A Simple Picture of Matching Lights

An illuminating engineer may need to match brightnesses in illuminated spaces, match colors of light sources or colors of illuminated objects, or see that his illumination reproduces color schemes. All these problems involve matching lights. Fortunately, the human visual system allows lights which are spectrally very different to match, i.e., appear indistinguishable. The human visual system requires, in order that two lights match in color and brightness, that three of their characteristics be identical. Recent work brings the identification of these three characteristics closer, highlights some simple common properties of matching lights, and suggests how illuminants should be designed.